Atomic clock: location and interesting facts

You have probably heard the term atomic clock, but you do not know exactly what it is and you do not know the location. In this article we will tell you from where this clock provides the exact time and a few background information on the atomic clock.

Atomic clock locations

Four atomic clocks are in operation in Germany. All are in the Physikalisch-Technische Bundesanstalt in Braunschweig.

• One of them, the cesium clock CS2, has given us the exact time since 1991. For example, your radio clock at home or on your arm receives the exact time from this atomic clock.
• Several atomic clocks are in operation in Austria. The Federal Office for Metrology and Surveying, headquartered in Vienna, is responsible for this.
• The atomic time TAI comes from an atomic clock in Switzerland. The Laboratory for Time and Frequency of the Federal Office of Metrology in Wabern near Bern also operates several atomic clocks.

Interesting facts about atomic clocks

Atomic clocks are known for their very precise time. This time has been standardized since 1967. The time unit used for this is one second.

• One second corresponds exactly to 9, 192, 631, 770 microwave vibrations of the cesium radiation. These vibrations are the basis of our atomic clocks and our time.
• As expected, the background to the operation of an atomic clock is physics, but also chemistry. Cesium isotope 133 is used for today's atomic clocks.
• The way it works is complicated. Put simply, an atomic clock like any other clock also consists of a counter and a clock.
• The cesium acts as a clock for the atomic clock. It is first evaporated in an oven and then bundled into a jet in a vacuum. The cesium atoms are then in the ground state.
• In a magnetic microwave field, the atoms change their state with a certain probability and are then counted.
• The microwave field is set so that as many atoms as possible are counted. For a second these are the 9, 192, 631, 770 microwave vibrations already mentioned above.
• The time is so exact because the radiation frequency of the cesium atom transitions is almost constant. This means that the atomic clock in Braunschweig only deviates by one billionth of a second every year.
• Incidentally, the atomic clock has not been around since the definition of the time unit second in 1967.
• The first atomic clock was developed in 1949, in the National Bureau of Standards in the United States. At that time, however, it was not cesium atoms but ammonia molecules.

In our next article on time, we'll tell you why the clock hand turns to the right.